Various methods of manufacturing elastic composite sheets to be used as components in wearing articles are known. For example, JP 2002-273808 A (PTL 1) discloses a method of manufacturing an elastic composite sheet including the steps of attaching elastics such as rubber strings to a sheet of, for example, a nonwoven fabric or a plastic film, and cutting these elastics to form elastic regions and inelastic regions in the elastic composite sheet for making a disposable diaper using this elastic composite sheet.